The present invention relates to a method of forming groups of cigarettes on a cigarette packing machine.
More specifically, the present invention relates to a method of forming groups of cigarettes on a cigarette packing machine capable of forming, substantially simultaneously, at least two groups of cigarettes, each forming the content of a packet of cigarettes.
On cigarette packing machines, groups of cigarettes are fed, at least in pairs, to at least one packing line by a supply device, which is fed in steps in a substantially horizontal direction, and comprises a number of pockets equally spaced along one or a number of parallel supply lines, and each for housing a respective group of cigarettes.
The cigarettes are fed to the group supply device by a hopper having an output end divided into a number of outlets arranged in at least two groups, each for forming a respective group of cigarettes. When each group of cigarettes is formed by superimposing layers, each group of outlets is defined by a number of outlets at most equal to the number of layers in each group of cigarettes. Conversely, when each group of cigarettes is formed in one go, each group of outlets is defined by a single outlet.
Each outlet is divided into a number of substantially vertical channels equal in number to the cigarettes in the respective layer or, if the groups of cigarettes are formed in one go, to the cigarettes in the longest layer in the respective group of cigarettes.
When each group of cigarettes comprises three superimposed layers and is formed by superimposing the layers, and when the hopper comprises, for example, three groups of three outlets each, the supply device moves forward in steps to position, at each stop, nine pockets beneath the output end of the hopper and aligned with the nine outlets. In this case, the output end of the hopper has nine push members, which are activated simultaneously to transfer, at each stop of the supply device, a layer of cigarettes into each of the nine pockets facing the respective push members.
The push members are so arranged that each of three first push members feeds a respective bottom layer into each of the three facing pockets; each of three second push members feeds a respective intermediate layer into each of the three facing pockets; and each of three third push members feeds a respective top layer into each of the three facing pockets. Since a complete group of cigarettes is formed inside a respective pocket in the course of three successive steps of the supply device, each pocket is therefore positioned, in the course of said steps, at the three outlets defining the same group of outlets.
When each group of cigarettes comprises two or more superimposed layers and is formed in one go at a respective outlet, and when the hopper comprises at least two outlets, which may be located over the same cigarette group conveyor line or over respective parallel lines, the supply device moves forward in steps to position, at each stop, two pockets beneath the output end of the hopper and aligned with the two outlets. In this case, the output end of the hopper has two push members, which are activated to transfer, at each stop of the supply device, a group of cigarettes into each of the two facing pockets.
A major drawback of both the above known forming devices lies in incomplete groups of cigarettes issuing from the hopperxe2x80x94and which must therefore be rejectedxe2x80x94whenever the flow of cigarettes along even only one channel of any one of the outlets is cut off by the presence, for example, of a cigarette positioned crosswise over the inlet of the channel.
To eliminate the above drawback, known forming devices of the above type normally comprise a stop signal emitter, which provides for total stoppage of the packing machine in response to a signal indicating no flow of cigarettes along even only one of the supply channels.
It is an object of the present invention to provide a method of forming groups of cigarettes, designed to eliminate the aforementioned drawbacks.
In particular, it is an object of the present invention to provide a method of forming groups of cigarettes, whereby stoppage of the outflow of cigarettes from an outlet of the hopper does not result in the formation of incomplete groups of cigarettes, let alone in total stoppage of the packing machine.
It is a further object of the present invention to provide a method of forming groups of cigarettes, which provides, if necessary, for reducing the output of a cigarette packing machine implementing the method.
According to the present invention, there is provided a method of forming groups of cigarettes on a cigarette packing machine; the packing machine comprising a hopper for supplying cigarettes; the hopper comprising at least two groups of outlets; each group of outlets comprising a number of outlets ranging between one and a number equal to the number of layers of cigarettes in each group of cigarettes; and the outlets in each group of outlets participating in forming a respective said group of cigarettes; the method being characterized by comprising the step of simultaneously intercepting respective streams of cigarettes issuing from all the outlets in a said group of outlets in response to a control signal.